Background: In the post highly active antiretroviral therapy (HAART) period, large numbers of people living with HIV/AIDS are aging. Persons with HIV infection have increased rates or altered clinical presentations of several neoplastic diseases such as cancer. At the same time, age is also a risk factor for many cancers. Thus, aging HIV/AIDS patients face the dual risk of non-AIDS defining cancers: infection related cancers and age related cancers. For people with HIV/AIDS who receive Social Security Disability Insurance (SSDI) benefits or those who live long enough to qualify, Medicare is an important source of health coverage. For effective health care planning, it is important to determine the incremental burden of non-AIDS defining cancers among Medicare HIV/AIDS patients. Study objective is to assess the incidence and prevalence rates of non-AIDS defining cancers, and the associated mortality rates and determine the marginal burden of non-AIDS defining cancers on health resource utilization and cost in Medicare HIV/AIDS patients. Specific aims: (1) To estimate non-AIDS defining cancer incidence and prevalence, non-AIDS defining cancer screening pattern and time to non-AIDS defining cancer treatment (from the date of non-AIDS defining cancer diagnosis) in Medicare patients with and without HIV/AIDS;(2) To analyze incremental burden of health resource utilization and the cost of care and mortality across four study groups;and (3) To examine extent that the HIV group differs from the comparison groups in age, race/ethnicity, gender and geographic location in the above estimates of non-AIDS defining cancer incidence and prevalence, health resource utilization, cost and mortality. Methods: To accomplish these aims, we propose a retrospective design using linked data from Surveillance, Epidemiology and End Results (SEER) data files and Medicare claims data. All Caucasian, African American and Hispanic persons aged 66 or older or those with SSDI benefits and diagnosed with any non-AIDS defining cancer between 1996 and 2005 will be identified. A control group of Medicare patients, free of any cancer, matched by age, gender, ethnicity and comorbidity will be obtained from the Medicare 5% sample from SEER. The following groups will be identified: (1) Medicare patients with any non-AIDS defining cancer and HIV/AIDS;(2) Medicare patients with any non-AIDS defining cancer and no HIV/AIDS;(3) Medicare patients with HIV/AIDS and no cancer;and (4) Medicare controls free of cancer and HIV/AIDS. All Medicare claims associated with the individuals in these groups will be obtained and person level records will be constructed. Statistical Analysis: Standardized Incidence ratios (SIR) (age, race and gender adjusted) will be compared between groups. Health resource utilization will be compared between groups longitudinally. Poisson regression (with zero inflation correction) will be used to assess health resource utilization. We will use GLM (log-link) models to estimate the incremental cost of cancer. We will explore if disparities (racial, gender, age and geography specific) exist in non-AIDS defining cancer incidence and prevalence, time to treatment of non-AIDS defining cancer (from date of diagnosis of non-AIDS defining cancer), health resource utilization, cost and mortality using parametric and non-parametric analysis. Conclusions: The AIDS epidemic is entering a chronic disease phase. The marginal burden of an additional chronic disease such as non-AIDS defining cancer in Medicare HIV patients can be significant. However, current research on this topic is limited. Thus, our study will provide valuable preliminary estimates of the incidence and prevalence of non-AIDS defining cancers in HIV Medicare population, and the marginal treatment and cost burden exerted by these non- AIDS defining cancers. Such information will aid in planning for the more effective management of Medicare patients with HIV. PUBLIC HEALTH RELEVANCE: The AIDS epidemic is entering a chronic disease phase. The marginal burden of an additional chronic disease such as non-AIDS defining cancer in Medicare HIV patients can be significant. However, current research on this topic is limited. Thus, our study will provide valuable preliminary estimates of the incidence and prevalence of non-AIDS defining cancers in HIV Medicare population, and the marginal treatment and cost burden exerted by such non-AIDS defining cancers. Such information will in planning for the more effective management of Medicare patients with HIV.